Various systems utilising X-ray fluorescence (XRF) techniques to analyse fluids, such as effluent waters of a chemical plant, are known in the prior art. FIG. 1 illustrates an example of such a system. The system of FIG. 1 comprises a flow cell 101 (shown as a cross-sectional view) having a body 102 that defines a cavity 103 through which the fluid to be analysed is passed. The fluid flows into the cavity 103 through an inlet pipe 104 and out of the cavity 103 through an outlet pipe 105. The inlet and outlet pipes 104, 105 are attached to opposite ends of the flow cell body 102 in such a manner that the directions of the inflowing and outflowing fluids are essentially the same. The flow cell 101 comprises an X-ray transparent window 106 through which the fluid that flows through the cavity 103 is irradiated with an X-ray source 107. The X-ray transparent window 106 is attached to the side of the flow cell body 102. The irradiated fluid emits fluorescent X-ray radiation that is transmitted through the X-ray transparent window 106 to be detected with an X-ray detector 108. The X-ray detector 108 measures the energy distribution of the fluorescent X-ray radiation in order to obtain information on the composition of the fluid.
A problem associated with the system of FIG. 1 is that, when a fluid flows through the flow cell, particles in the fluid adhere easily on the surface of the X-ray transparent window. As a result of this the compositional analysis of the fluid is difficult or even impossible to carry out as the material adhered to the X-ray transparent window prevents the analysis of the fluid that flows through the cavity.
Another problem associated with the system of FIG. 1 is that, when a fluid flows through the flow cell, heavier particles are easily separated from the lighter particles. This results in incorrect readings at the point of measurement.